The erect position typical of mankind is intrinsically unstable due to the action of gravity and maintaining it, that is to say, the ability to keep one's balance, is a basic requirement for body movement.
Closely linked to this are the abilities to carefully control one's posture and to effectively co-ordinate the movements of the different parts of the body.
Therefore, the control of balance, posture and co-ordination have a role of central importance in the wider context of motor control and substantially depend on the subject's perception of the spatial positioning of his/her body or part of it.
It is known that ageing and any neural, muscular or skeletal disorder which compromises the senses may, in practice, result in a diminished motor ability and, in particular, a higher risk of postural instability and falls.
For this reason, the invention of systems for training, maintaining, rehabilitating or monitoring motor ability which have positive effects on balance, posture and motor co-ordination is currently strategic in a society in which the average age is gradually increasing.
Devices have been invented which help maintain balance, for people with motor difficulties and, in particular, devices able to provide the user with information about the spatial orientation of at least one part of his/her body.
Consider, for example, the device described in U.S. Pat. No. 6,546,291, which generally comprises an acquisition system, preferably wearable by the user, for detecting the spatial orientation and movement of the user or part of his/her body.
The acquisition system communicates, by means of a communication interface and an encoder, with a stimulator apparatus connected to the user's nervous system.
The stimulator apparatus comprises at least one electrode, located close to one of the user's nerves, by means of which a signal, suitably generated by the encoder according to the spatial orientation detected, stimulates said nerve, providing the user with an indication of his/her spatial orientation.
The device has several disadvantages, in particular direct stimulation of the nerve is not always easy to achieve and correct positioning of the electrode for this purpose may be awkward and ineffective, particularly in the case of elderly users.
The device also being dedicated to people with motor difficulties, these people may find it difficult to position and secure the stimulating electrodes on the body and guarantee that they remain in the correct position.